'Baedeker' originates from German, specifically the surname 'Baedeker' (the family name of Karl Baedeker), the founder of a 19th-century travel-guide publishing firm.

'Baedeker' changed from being merely the surname of the founder to being used to refer to the travel guidebooks published by his firm; the plural 'Baedekers' referred to those books.

Initially it meant 'the name of the publisher / the family name,' but over time it evolved into the current meaning of 'a travel guidebook' and is sometimes used generically for guidebooks.